Many of the Handel operas now held in such high esteem began life, we tend to forget, as oratorios. Bach wrote no operas, so it made inspired sense when Jonathan Miller pioneered stage versions of such choral works as the St Matthew Passion. Michael Tippett wrote five, so why did one of our leading opera companies choose to mark his centenary by mounting an unprecedented staging of his only oratorio?

More of that later, as seen through the prism of a handsome, intelligent new production of Tippett's third opera, The Knot Garden. Premiered at Covent Garden in 1970, it is due no fewer than three revivals this year, including a BBC Symphony 'concert staging'. But a high benchmark has been set by Antony McDonald's imaginative reading for Scottish Opera, which defies its successors to bring this Sixties period piece as vividly to contemporary life.

Tippett was the prototype superannuated hippie - in his sixties in the Sixties, yet as thrilled as any Carnaby Street groupie by all the swinging goings-on, from the musical to the socio-political. There are, for instance, parts for electric guitar and jazz kit scored in the composer's heavily Jungian update of Shakespeare's The Tempest, in which Prospero becomes a shrink named Mangus.

With a dysfunctional couple whose spaced-out teenage ward is a 20th-century Alice in Wonderland, a war-wounded freedom-fighter, plus the first gay couple known to opera, this is a sub-Iris Murdoch novel turned into music theatre. Writing his own text, on the advice of TS Eliot, Tippett drew on Hamlet, Lear and All's Well as much as The Tempest, not to mention Shaw, Fry, Albee and Eliot himself, while reflecting musical influences from Schubert to the blues.

The result is an engaging mess, full of half-baked paperback psychology of the voguish van der Post school, offering wide-eyed optimism that no life is too screwed up to benefit from psycho-babbling group interaction and other therapeutic routes towards an improbably better (and thus brave new) world.

At least Tippett was grappling with issues of the day, however naively, while clinging to reshaped cultural traditions. Amid a score as neophiliac as the text, the work's most effective moment comes when time stands still for the ditsy teenager to sing an exquisitely orchestrated Schubert song. Otherwise, the blues and boogie-woogie come to the composer's rescue, notably in the powerful septet which climaxes the first act, as surely as spirituals do in this week's other case in point.

McDonald's Mad Hatter set serves his production well, facilitating the swift scene-shifts and movie-style dissolves that characterise the composer's self-consciously innovative libretto, for all its clunky one-liners. That Tippett actually believed in all this period pap is, when it is so well-done, rather touching. That Scotland's politicians should allow so fine a company to disappear down a financial plughole, rather than supporting it with due national pride, is quite the reverse.

Given the company's deficit and Tippett's minimalist box-office pull, Scottish Opera was perhaps wise to schedule only six performances, despite the evident investment of so much thought and effort. In even more tentative mode, English National Opera offered just two performances of Tippett's oratorio, A Child of Our Time, after no less ingenuity from director Jonathan Kent.

If you must stage a work intended for concert performance, by a composer who wrote plenty of other material specifically for the stage, it is hard to imagine a more effective version than Kent's, shot through with heavy symbolism of which Tippett would surely have approved.

Weapons that descended from the flies reascended as lights, presumably signifying hope, later redescending as stones (ritual tasks in concentration camps) before becoming turf (making the desert bloom). A trap revealed the eponymous child's family, represented by actors for whom the singers doubled in authentically Jungian fashion, later becoming the child's grave, then a tree planted upon it, which finally burst into flames, suggesting, presumably, the composer's perennial obsession with progress from darkness to light.

Tippett's 'child' was inspired by a 17-year-old Polish Jew named Herschel Grynspan, who avenged Nazi persecution of his family by shooting a German diplomat in Paris in 1938, precipitating the pogrom notorious as Kristallnacht. Represented by a tenor (Timothy Robinson), he is one of four soloists, alongside a soprano (Susan Gritton) who doubles as his mother, an alto (Sara Fulgoni) as a quasi-aunt, and a bass (Brindley Sherratt) as both father and narrator.

In the staging, these parts necessarily became more specific than in the text, where each singer is allotted more generalised sentiments. Likewise, the multiple roles given the chorus were conveyed by changes of emphasis, if not mood. Kent did as much as humanly possible to inject theatrical life into a piece inevitably so downbeat.

But the net result was unavoidably super-solemn, lurching between the over-literalistic and the portentous, with people in black standing around emoting via permanently stricken expressions. It didn't help that so few of the words were audible, especially from Fulgoni and the chorus, which was not entirely the fault of Martyn Brabbins's over-forceful conducting. It is little use handing the audience a text unless you keep up the house lights so we can follow it. But, then, this is theatre. Isn't it?

The picture on the front of ENO's programme, showing children playing on an abandoned tank, evokes obvious parallels with the contemporary Middle East and Afghanistan. But so, just as powerfully, without any stage artifice, did last summer's Proms performance of Britten's War Requiem. Both composers were surely right in their conscious decision that, with this kind of subject matter, their pacifist protests were better heard than seen.

Three to see

La Traviata Covent Garden, London WC2, tomorrow to 15 Feb Two casts to choose from in venerable Richard Eyre production.